Plasma processing device

ABSTRACT

In a microwave plasma processing apparatus, the reflection of microwave by the joint unit between the microwave supplying waveguide and the microwave antenna is reduced by providing a taper surface or a member having a medium permittivity between the microwave supplying waveguide and the microwave antenna so as to moderate an impedance change. Accordingly, the efficiency of power supplying is improved, and reduced discharge ensures stable formation of plasma.

TECHNICAL FIELD

[0001] The present invention is generally related to a plasma processingapparatus, and more particularly, to a microwave plasma processingapparatus.

[0002] Plasma processing and plasma processing apparatuses are anindispensable technology for fabricating ultrafine semiconductor devicesthese days called deep submicron devices or deep subquarter microndevices characterized by a gate length of near 0.1 μm or less, and forfabricating ultra high-resolution flat-panel display devices includingliquid crystal display devices.

[0003] Conventionally, various plasma excitation methods have been usedin plasma processing apparatuses used for fabrication of semiconductordevices and liquid crystal display devices. Particularly, aparallel-plate type high-frequency excitation plasma processingapparatus or an induction-coupled plasma processing apparatus arecommonly used. However, such conventional plasma processing apparatuseshave a drawback of non-uniform plasma formation in that the region ofhigh electron density is limited, and it has been difficult to conduct auniform process over the entire substrate surface with a high processingrate, and hence with high throughput. This problem becomes particularlyacute when processing a large diameter substrate. Further, such aconventional plasma processing device has several inherent problemsassociated with its high electron temperature, in that the semiconductordevices formed on the substrate sustain damage and that significantmetal contamination is caused as a result of sputtering of a chamberwall. Thus, there are increasing difficulties for such conventionalplasma processing apparatuses to meet the stringent demand of furtherdevice miniaturization and further improvement of productivity inmanufacturing semiconductor devices and liquid crystal display devices.

[0004] Meanwhile, there are proposals of a microwave plasma processingapparatus that uses high-density plasma excited by a microwave electricfield, in place of a direct-current magnetic field. For example, thereis a proposal of a plasma processing apparatus that causes excitation ofplasma by radiating a microwave into a processing vessel from a planarantenna (radial line slot antenna) having a number of slots disposed soas to form a uniform microwave, such that the microwave electric fieldcauses ionization of a gas in a vacuum vessel. (See for example JapaneseLaid-Open Patent Application 9-63793). In the microwave plasma thusexcited, it is possible to realize a high plasma density over a widearea right underneath the antenna, and it becomes possible to conductuniform plasma processing in a short duration. The microwave plasma thusformed is characterized by low electron temperature, and damaging ormetal contamination of the substrate is avoided. Further, it is possibleto form uniform plasma over a large surface area, and it can be easilyapplied to the fabrication process of a semiconductor device using alarge diameter semiconductor substrate and a large size liquid crystaldisplay device.

BACKGROUND ART

[0005]FIGS. 1A and 1B show the construction of a conventional microwaveplasma processing apparatus 100 having such a radial line slot antenna,wherein FIG. 1A shows the microwave plasma processing apparatus in across-sectional view while FIG. 1B shows the construction of the radialline slot antenna.

[0006] Referring to FIG. 1A, the microwave plasma processing apparatus100 has a processing chamber 101 evacuated from plural evacuation ports116, and a stage 115 is formed for holding a substrate 114 to beprocessed. In order to realize uniform evacuation in the processingchamber 101, a ring-shaped space 101A is formed around the stage 115,and the plural evacuation ports 116 are formed in communication with theforegoing space 101A at a uniform interval, and hence in axial symmetrywith regard to the substrate. Thereby, it becomes possible to evacuatethe processing chamber 101 uniformly through the space 101A and theevacuation ports 116.

[0007] On the processing chamber 101, there is formed a shower plate 103of plate-like form at the location corresponding to the substrate 114 onthe stage 115 as a part of the outer wall of the processing chamber 101,and the shower plate 103 is sealed with respect to the processingchamber 101 via a seal ring 109, wherein the shower plate 103 is formedof a dielectric material of small loss and includes a large number ofapertures 107. Further, a cover plate 102 also of a dielectric materialof small loss is provided on the outer side of the shower plate 103, andthe cover plate 102 is sealed with respect to the shower plate 103 viaanother seal ring 108.

[0008] The shower plate 103 is formed with a passage 104 for a plasmagas on the top surface thereof, and each of the plural apertures 107 areformed in communication with the foregoing plasma gas passage 104.Further, there is formed a plasma gas supply passage 108 in the interiorof the shower plate 103 in communication with a plasma gas supply port105 provided on the outer wall of the processing vessel 101. Thus, theplasma gas of Ar, Kr or the like supplied to the foregoing plasma gassupply port 105 is supplied to the foregoing apertures 107 from thesupply passage 108 via the passage 104 and is released into a space 101Bunderneath the shower plate 103 in the processing vessel 101 from theapertures 107 with substantially uniform concentration.

[0009] On the processing vessel 101, there is provided a radial lineslot antenna 110 having a radiation surface shown in FIG. 1B on theouter side of the cover plate 102 with a separation of 4-5 mm from thecover plate 102. The radial line slot antenna 110 is connected to anexternal microwave source (not shown) via a coaxial waveguide 110A andcauses excitation of the plasma gas released into the space 101B by themicrowave from the microwave source. It should be noted that the gapbetween the cover plate 102 and the radiation surface of the radial lineslot antenna 110 is filled with air.

[0010] The radial line slot antenna 110 is formed of a flat disk-likeantenna body 110B connected to an outer waveguide of the coaxialwaveguide 110A and a radiation plate 110C is provided on the mouth ofthe antenna body 110B, wherein the radiation plate 110C is formed with anumber of slots 110 a and slots 110 b wherein slots 110 b are formed ina direction crossing the slots 110 a perpendicularly as represented inFIG. 1B. Further, a retardation plate 110D of a dielectric film ofuniform thickness is inserted between the antenna body 110B and theradiation plate 110C.

[0011] In the radial line slot antenna 110 of such a construction, themicrowave supplied from the coaxial waveguide 110 spreads between thedisk-like antenna body 110B and the radiation plate 110C as it ispropagated in the outward radial directions, wherein there occurs acompression of wavelength as a result of the action of the retardationplate 110D. Thus, by forming the slots 110 a and 110 b in concentricrelationship in correspondence to the wavelength of the radiallypropagating microwave so as to cross perpendicularly with each other, itbecomes possible to emit a plane wave having a circular polarizationstate in a direction substantially perpendicular to the radiation plate110C.

[0012] By using such a radial line slot antenna 110, uniform plasma isformed in the space 101B underneath the shower plate 103. Thehigh-density plasma thus formed is characterized by a low electrontemperature and thus no damage is caused to the substrate 114 and nometal contamination occurs due to sputtering of the vessel wall of theprocessing vessel 101.

[0013] In the plasma processing apparatus of FIG. 1, it should furtherbe noted that there is provided a conductor structure 111 in theprocessing vessel 101 between the shower plate 103 and the substrate114, wherein the conductor structure 111 is formed with a number ofnozzles 113 supplied with a processing gas from an external processinggas source (not shown) via a processing gas passage 112 formed in theprocessing vessel 101, and each of the nozzles 113 releases theprocessing gas supplied thereto into a space 101C between the conductivestructure 111 and the substrate 114. It should be noted that theconductive structure 111 is formed with openings between adjacentnozzles 113 with a size such that the plasma formed in the space 101Bpasses efficiently from the space 101B to the space 101C by way ofdiffusion.

[0014] Thus, in the case wherein a processing gas is released into thespace 101C from the conductive structure 111 via the nozzles 113, theprocessing gas is excited by the high-density plasma formed in the space101B and uniform plasma processing is conducted on the substrate 114efficiently and at a high rate, without damaging the substrate or thedevices on the substrate, and without contaminating the substrate.Further, it should be noted that the microwaves emitted from the radialline slot antenna 110 are blocked by the conductive structure 111 andthere is no possibility of such microwaves causing damage to thesubstrate 114.

[0015] By the way, it is necessary in the case of the plasma processingapparatus 100 to efficiently supply high-power microwaves formed by amicrowave source (not shown) to the radial line slot antenna 110.

[0016] An impedance matching structure is generally provided between amicrowave antenna and a waveguide connected to the microwave antenna toinject a weak microwave signal received by the microwave antenna intothe waveguide without loss. Meanwhile, in the case of the plasmaprocessing apparatus 100 of FIG. 1, high-power microwaves are providedto the radial line slot antenna 110 through the waveguide, andadditionally, reflective microwaves reflected by the plasma formed inthe processing vessel 101 are also superimposed on the high-powermicrowaves in the antenna 110 and the waveguide. There is a possibilityof abnormal discharge being caused in the radial line slot antenna 110and the coaxial waveguide due to inappropriate impedance matchingbetween the antenna body 110 and the waveguide. Accordingly, theimpedance matching of the power supply unit connecting the waveguide andthe antenna body 110 is much more important than usual.

DISCLOSURE OF THE INVENTION

[0017] Accordingly, it is an object of the present invention to providea novel and useful plasma processing apparatus wherein the foregoingproblems are eliminated.

[0018] Another and more specific object of the present invention is toprovide a plasma processing apparatus having a microwave antenna,forming plasma in the processing vessel by providing microwaves from themicrowave antenna to the processing vessel through the microwavetransparent window, and processing the substrate in the plasma, in whichthe efficiency of supplying microwaves from the microwave waveguide tothe microwave antenna is increased, and the abnormal discharge problemdue to the mismatching of impedance at the joint unit between themicrowave waveguide and the microwave antenna is eliminated.

[0019] Yet another object of the present invention is to provide aplasma processing apparatus, comprising, a processing vessel defined byan outer wall and having a stage for holding a substrate to beprocessed, an evacuation system coupled to said processing vessel, amicrowave transparent window provided on said processing vessel as apart of said outer wall, and opposite said substrate held on said stage,a plasma gas supplying part for supplying plasma gas to said processingvessel, a microwave antenna provided on said processing vessel incorrespondence to said microwave, and a microwave power sourceelectrically coupled to said microwave antenna, wherein said microwaveantenna comprising a coaxial waveguide connected to said microwave powersource, said coaxial waveguide having an inner conductor core and anouter conductor tube surrounding said inner conductor core, and anantenna body provided to a point of said coaxial waveguide, said antennabody further comprising a first conductor surface forming a microwaveradiation surface coupled with said microwave transparent window, and asecond conductor surface opposite said first conductor surface via adielectric plate, said second conductor surface being connected to saidfirst conductor surface at a peripheral part of said dielectric plate,said inner conductor core is connected to said first conductor surfaceby a first joint unit, said outer conductor tube is connected to saidsecond conductor surface by a second joint unit, said first joint unitforms a first taper unit in which an outer diameter of said innerconductor core increases toward said first conductor surface, and saidsecond joint unit forms a second taper unit in which an inner diameterof said outer conductor tube increases toward said first conductorsurface.

[0020] Another object of the present invention is to provide a plasmaprocessing apparatus, comprising, a processing vessel defined by anouter wall and having a stage for holding a substrate to be processed,an evacuation system coupled to said processing vessel, a microwavetransparent window provided on said processing vessel as a part of saidouter wall, opposite said substrate held on said stage, a plasma gassupplying part for supplying plasma gas to said processing vessel, amicrowave antenna provided on said processing vessel in correspondenceto said microwave, and a microwave power source electrically coupled tosaid microwave antenna, wherein said microwave antenna comprising acoaxial waveguide connected to said microwave power source, said coaxialwaveguide having an inner conductor core and an outer conductor tubesurrounding said inner conductor core, and an antenna body provided to apoint of said coaxial waveguide, said antenna body further comprising afirst conductor surface forming microwave a radiation surface coupledwith said microwave transparent window and a second conductor surfaceopposite said first conductor surface via a dielectric plate, saidsecond conductor surface being connected to said first conductor surfaceat a peripheral part of said dielectric plate, said inner conductor coreis connected to said first conductor surface by a first joint unit, saidouter conductor tube is connected to said second conductor surface by asecond joint unit, a dielectric member is provided in a space betweensaid inner conductor core and said outer conductor tube, defined by afirst edge face and a second edge face opposing said first edge face,said first edge face being adjacent to said dielectric plate, apermittivity of said dielectric member being lower than a permittivityof said dielectric plate and higher than a permittivity of air.

[0021] According to the present invention, the rapid change in impedanceby the joint unit between the microwave waveguide and the microwaveantenna is avoided. As a result, microwaves reflected by the joint unitare efficiently reduced. As the reflective waves are reduced, abnormaldischarge at the joint unit and consequent damage on the antenna causedby the abnormal discharge is avoided. Additionally, the reduction in thereflective waves stabilizes the supply of microwaves to the processingvessel through the microwave transparent window, and makes it possibleto form stable plasma in the processing vessel as desired.

[0022] Other features and advantages of the present invention willbecome more apparent from the following best mode for implementing theinvention when read in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023]FIGS. 1A and 1B are diagrams showing the construction of aconventional microwave plasma processing apparatus that uses a radialline slot antenna;

[0024]FIGS. 2A and 2B are diagrams showing the construction of amicrowave plasma processing apparatus according to a first embodiment ofthe present invention;

[0025]FIGS. 3A and 3B are diagrams showing the construction of the jointbetween a coaxial waveguide and a radial line slot antenna of theapparatus of FIG. 2;

[0026]FIG. 4 is a graph showing the effect of eliminating reflection bythe construction of FIG. 3;

[0027]FIG. 5 is a graph showing the reflection coefficient measured forthe microwave plasma formed in the plasma processing apparatus of FIGS.2A and 2B using the power supplying structure of FIG. 3;

[0028]FIG. 6 is a diagram showing the construction of the process gassupplying structure of the microwave plasma processing apparatus shownin FIG. 2A;

[0029]FIG. 7 is a diagram showing the construction of the microwavepower source coupled to the microwave plasma processing apparatus ofFIG. 2A;

[0030]FIG. 8 is a diagram showing the construction of a microwavesupplying structure according to a variation of the present embodiment;

[0031]FIG. 9 is a diagram showing the construction of a microwavesupplying structure according to a second embodiment of the presentinvention;

[0032]FIG. 10 is a diagram showing a variation of the microwavesupplying structure of FIG. 9;

[0033]FIG. 11 is a diagram showing another variation of the microwavesupplying structure of FIG. 9;

[0034]FIG. 12 is a diagram showing another variation of the microwavesupplying structure of FIG. 9;

[0035]FIG. 13 is a diagram showing yet another variation of themicrowave supplying structure of FIG. 9;

[0036]FIG. 14 is a diagram showing yet another variation of themicrowave supplying structure of FIG. 9;

[0037]FIG. 15 is a diagram showing the construction of microwave plasmaprocessing apparatus according to a third embodiment of the presentinvention;

[0038]FIG. 16 is a diagram showing the construction of microwave plasmaprocessing apparatus according to a fourth embodiment of the presentinvention;

[0039]FIG. 17 is a diagram showing the construction of microwave plasmaprocessing apparatus according to a fifth embodiment of the presentinvention;

[0040]FIG. 18 is a diagram showing the construction of a semiconductorfabrication apparatus according to a sixth embodiment of the presentinvention, using the microwave plasma processing apparatus of FIGS. 2Aand 2B;

[0041]FIG. 19 is a diagram showing the construction of an exhaustionsystem of the semiconductor fabrication apparatus of FIGS. 18A and 18B;

[0042]FIG. 20 is a diagram showing the construction of a screw molecularpump used for the exhaustion system of FIG. 19;

[0043]FIG. 21 is a diagram showing the construction of a gradationallead screw pump used for the exhaustion system of FIG. 19;

[0044]FIG. 22 is a diagram showing the construction of a gas supplyingsystem used for the processing unit of FIG. 19; and

[0045]FIG. 23 is a diagram showing the construction of a current controlapparatus used for the gas supplying system of FIG. 22.

BEST MODE FOR IMPLEMENTING THE INVENTION

[0046] Preferred embodiments of the present invention will be describedbelow.

[0047] [First Embodiment]

[0048]FIGS. 2A and 2B are diagrams showing the construction of amicrowave plasma processing apparatus 10 according to a first embodimentof the present invention.

[0049] Referring to FIG. 2A, the microwave plasma processing apparatus10 includes a processing vessel 11 and a stage 13 provided in theprocessing vessel 11 for holding a substrate 12 to be processed by anelectrostatic chuck, wherein the stage 13 is preferably formed of AlN orAl₂O₃ by a hot isostatic pressing (HIP) process. In the processingvessel 11, there are formed two or three evacuation ports 11 a in aspace 11A surrounding the stage 13 with an equal distance, and hencewith an axial symmetry with respect to the substrate 12 on the stage 13.The processing vessel 11 is evacuated to a low pressure via theevacuation ports 11 a by a gradational lead screw pump.

[0050] The processing vessel 11 is preferably formed of an austenitestainless steel containing Al, and there is formed a protective film ofaluminum oxide on the inner wall surface by an oxidizing process.Further, there is formed a disk-shaped shower plate 14 of dense Al₂O₃,formed by a HIP process, in the part of the outer wall of the processingvessel 11 corresponding to the substrate 12 as a part of the outer wall,wherein the shower plate 14 includes a large number of nozzle apertures14A. The Al₂O₃ shower plate 14 thus formed by the HIP process is formedby using an Y₂O₃ additive and has porosity of 0.03% or less. This meansthat the Al₂O₃ shower plate is substantially free from pores or pinholesand has a very large, while not so large as that of AlN, thermalconductivity for a ceramic of 30W/m·K.

[0051] The shower plate 14 is mounted on the processing vessel 11 andsealed thereto via a seal ring 11 s, and a cover plate 15 of dense Al₂O₃formed also by an HIP process is provided on the shower plate 14 andsealed thereto via a seal ring lit. The shower plate 14 is formed with adepression 14B communicating with each of the nozzle apertures 14A andserving as a plasma gas passage, a side thereof formed by the coverplate 15. The depression 14B also communicates with another plasma gaspassage 14C formed in the interior of the shower plate 14 incommunication with a plasma gas inlet 11 p formed on the outer wall ofthe processing vessel 11.

[0052] The shower plate 14 is held by an extending part 11 b formed onthe inner wall of the processing vessel 11, wherein the extending part11 b is formed with a round surface,at the part holding the shower plate14 so as to suppress electric discharge.

[0053] Thus, plasma gas such as Ar or Kr supplied to the plasma gasinlet 11 p is supplied to a space 11B underneath the shower plate 14uniformly via the apertures 14A after being passed through the passage14C and the depression 14B in the shower plate 14.

[0054] On the cover plate 15, there is provided a radial line slotantenna 20 formed,of a disk-shaped slot plate 16 formed with a number ofslots 16 a and 16 b shown in FIG. 3B in intimate contact with the coverplate 15, a disk-shaped antenna body 17 holding the slot plate 16, and aretardation plate 18 of a dielectric material of low loss such as Al₂O₃,SiO₂ or Si₃N₄ sandwiched between the slot plate 16 and the antenna body17. The radial line slot antenna 20 is mounted on the processing vessel11 and sealed thereto by way of a seal ring 11 u, and a microwave of2.45 GHz or 8.3 GHz frequency is fed to the radial line slot antenna 20from an external microwave source (not shown) via a coaxial waveguide21. The microwave thus supplied is radiated into the interior of theprocessing vessel from the slots 16 a and 16 b in the slot plate 16 viathe cover plate 15 and the shower plate 14. Thereby, the microwavescause excitation of plasma in the plasma gas supplied from the apertures14A in the space 11B underneath the shower plate 14. It should be notedthat the cover plate 15 and the shower plate 14 are formed of Al₂O₃ andfunction as an efficient microwave-transmitting window. In order toavoid plasma excitation in the plasma gas passages 14A-14C, the plasmagas is held at a pressure of about 6666 Pa-13332 Pa (about 50-100 Torr)in the foregoing passages 14A-14C.

[0055] In order to improve intimate contact between the radial line slotantenna 20 and the cover plate 15, the microwave plasma processingapparatus 10 of the present embodiment has a ring-shaped groove 11 g ina part of the processing vessel 11 so as to be adjacent to the slotplate 16. By evacuating the groove 11 g via an evacuation port 11Gcommunicating therewith, the pressure in the gap formed between the slotplate 16 and the cover plate 15 is reduced and the radial line slotantenna 20 is urged firmly upon the cover plate 15 by the atmosphericpressure. It is noted that such a gap includes not only the slots 16 aand 16 b formed in the slot plate 16 but also a gap formed for variousother reasons. It should be noted further that such a gap is sealed bythe seal ring 11 u provided between the radial line slot antenna 20 andthe processing vessel 11.

[0056] By filling the gap between the slot plate 16 and the cover plate15 with an inert gas of small molecular weight via the evacuation port11G and the groove 11 g, heat transfer from the cover plate 15 to theslot plate 16 is facilitated. It is preferable to use He for such aninert gas in view of large thermal conductivity and large ionizationenergy. In the case wherein the gap is filled with He, it is preferableto set the pressure to about 0.8 a tm. In the construction of FIG. 3,there is provided a valve 11V on the evacuation port 11G for theevacuation of the groove 15 g and filling of the inert gas into thegroove 15 g.

[0057] It is noted that an outer waveguide 21A of the coaxial waveguide21A is connected to the disk-shaped antenna body 17 while a centerconductor 21B is connected to the slot plate 16 via an opening formed inthe retardation plate 18. Thus, the microwave fed to the coaxialwaveguide 21A is propagated in the outer radial directions between theantenna body 17 and the slot plate 16 and is emitted from the slots 16 aand 16 b.

[0058]FIG. 2B shows the slots 16 a and 16 b formed in the slot plate 16.

[0059] Referring to FIG. 2B, the slots 16 a are arranged concentrically,and the slots 16 b, each corresponding to a slot 16 a and beingperpendicular to the corresponding slot 16 a, are also arrangedconcentrically. The slots 16 a and 16 b are formed with an intervalcorresponding to the wavelength of the microwave compressed by theretardation plate 18 in the radial direction of the slot plate 16, andas a result, the microwave is radiated from the slot plate 16 in theform of a near plane wave. Because the slots 16 a and the slots 16 b areformed in a mutually perpendicular relationship, the microwave thusradiated forms a circularly polarized wave including two perpendicularpolarization components.

[0060] In the plasma processing apparatus 10 of FIG. 2A, there isprovided a cooling block 19 formed with a cooling water passage 19A onthe antenna body 17, and the heat accumulated in the shower plate 14 isabsorbed via the radial line slot antenna 20 by cooling the coolingblock 19 with cooling water in the cooling water passage 19A. Thecooling water passage 19A is formed on the cooling block 19 in a spiralform, and cooling water having a controlled oxidation-reductionpotential is supplied thereto, wherein the control of the oxidationreduction potential is achieved by eliminating oxygen dissolved in thecooling water by way of bubbling of an H₂ gas.

[0061] In the microwave plasma processing apparatus 10 of FIG. 2A, thereis further provided a process gas supply structure 31 in the processingvessel 11 between the shower plate 14 and the substrate 12 on the stage13, wherein the process gas supply structure 31 has gas passages 31Aarranged in a lattice shape and releases a process gas supplied from aprocess gas inlet port 11 r provided in the outer wall of the processingvessel 11 through a large number of process gas nozzle apertures 31B(see FIG. 4). Thereby, desired uniform substrate processing is achievedin a space 11C between the process gas supply structure 31 and thesubstrate 12. Such substrate processing includes plasma oxidationprocessing, plasma nitridation processing, plasma oxynitridationprocessing, and plasma CVD processing. Further, it is possible toconduct a reactive ion etching of the substrate 12 by supplying areadily decomposing fluorocarbon gas such as C₄F₈, C₅F₈ or C₄F₆ or anetching-gas containing F or Cl from the process gas supply structure 31to the space 11C and further by applying a high-frequency voltage to thestage 13 from a high-frequency power source 13A.

[0062] In the microwave plasma processing apparatus 10 of the presentembodiment, it is possible to avoid deposition of reaction byproducts onthe inner wall of the processing vessel by heating the outer wall of theprocessing vessel 11 to a temperature of about 150° C. Thereby, themicrowave plasma processing apparatus 10 can be operated constantly andwith reliability, by merely conducting a dry cleaning process once a dayor so.

[0063] In the case of the plasma processing apparatus 10 of FIG. 2A, ataper unit 21Bt of the center conductor 21B is formed at the joint/powersupplying unit that connects the coaxial waveguide 21 to the radial lineslot antenna 20, so that the radius or the cross sectional area of thecenter conductor 21B gradually increases towards the slot plate 16.Thus, the rapid change in impedance caused by the joint/power supplyunit is smoothed by forming such a taper structure, which results in agreat reduction of reflective waves caused by the rapid change inimpedance.

[0064]FIG. 3A is an expanded diagram showing in detail the constructionof the joint/microwave supplying unit between the coaxial waveguide 21and the radial line slot antenna 20 of the plasma processing apparatus10 of FIG. 2A. The slots 16 a and 16 b formed on the slot plate 16 arenot shown to simplify the drawing.

[0065] Referring to FIG. 3A, the inner conductor 21B has a circularcross section having a diameter of 16.9 mm. A 4 mm-thick alumina platehaving a relative permittivity of 10.1 is formed between the slot plate16 and the antenna body 17 as the retardation plate 18. The outerwaveguide 21A defines a cylindrical space having a circular crosssection having an inner diameter of 38.8 mm in which the inner conductor21B is provided.

[0066] As shown in FIG. 3A, the cross sectional area of the innerconductor 21B is gradually increased from 7 mm above the joint betweenthe inner conductor 21B and the slot plate 16 to the joint. As a result,the inner conductor 21B has a circular cross section of a diameter of 23mm at the joint. Additionally, the antenna body 17 is provided with ataper surface 21At corresponding to the taper surface 21Bt thus formed,the taper surface 21At starting from the position 10 mm (the thicknessof the retardation plate 18 4 mm+the thickness of the antenna body 17 6mm=10 mm) above the joint of the inner conductor 21B and the slot plate16.

[0067]FIG. 4 shows the reflective ratio of microwave provided to theantenna 20 through the waveguide 21 in the case where the radial lineslot antenna 20 and the waveguide 21 are used as shown in FIG. 3A, andthe parameter “a” shown in FIG. 3A is set at 6.4 mm. In FIG. 4, thereflective ratio is indicated by “•”. In addition, “*” shown in FIG. 4indicates a reflective ratio of the construction shown in FIG. 3B towhich the taper units 21At and 21Bt are not provided.

[0068] Referring to FIG. 4, the reflective microwave includes not onlythe microwave reflected by the joint/supplying unit between thewaveguide 21 the radial line antenna 20, but also the microwavereflected by the plasma. In the case of the construction of FIG. 3B, thereflective ratio is about −2 dB regardless of a frequency, which meansabout 80% of the microwave is reflectively returned to the waveguide 21and the microwave source connected to the waveguide 21.

[0069] To the contrary, in the case of the construction of FIG. 3A towhich the taper surfaces 21At and 21Bt are provided, the reflectiveratio depends on the frequency of the microwave. The reflective ratiobecomes the minimum −23 dB (about 14%) in the neighborhood of 2.4 GHz atwhich the plasma is excited.

[0070]FIG. 5 shows a microwave reflection factor measured by a powermonitor provided between the waveguide 21 and the microwave source inthe case of the antenna construction shown in FIG. 3A under thefollowing condition: the inner pressure in the processing vessel beingset at 133 Pa (about 1 Torr), Ar and 0 ₂ being supplied from the showerplate 14 at a flux of 690 SCCM and 23 SCCM, respectively, and microwavesof a frequency 2.45 GHz and a power of 1.6 kW is supplied from thewaveguide 21 to the radial line slot antenna 20. Accordingly, thereflective factor includes not only the reflection of microwave by thejoint between the waveguide 21 and the antenna 20, but also thereflection by the plasma formed under the shower plate 14 in theprocessing vessel 11.

[0071] Referring to FIG. 5, it is noted that in the case of the jointconstruction of FIG. 3B, the reflective ratio is about 80% (the factorof reflection ≈0.8), but in the case of the joint construction of FIG.3A, the reflective ratio is reduced to about 30% (the factor ofreflection ≈0.3) and substantially constant. Since the reflection ratioat the joint unit between the coaxial waveguide 21 and the radial lineantenna 20 is about 14% as shown in FIG. 4, the reflective ratio ofabout 30% as shown in FIG. 5 includes the reflection by the plasma.

[0072]FIG. 6 is a bottom view showing the construction of the processgas supply structure 31 of FIG. 2A.

[0073] Referring to FIG. 6, the process gas supply structure 31 isformed by a conductive body such as an Al alloy containing Mg or astainless steel added with Al. The lattice shaped gas passage 31A isconnected to the process gas inlet port 11 r at a process gas supplyport 31R and releases the process gas uniformly into the foregoing space11C from the process gas nozzle apertures 31B formed at the bottomsurface. Further, openings 31C are formed in the process gas supplystructure 31 between the adjacent process gas passages 31A for passingthe plasma or the process gas contained in the plasma therethrough. Inthe case wherein the process gas supply structure 31 is formed of an Alalloy containing Mg, it is preferable to form a fluoride film on thesurface thereof. In the case wherein the process gas supplying structure31 is formed of a stainless steel added with Al, it is preferable toform a passivation film of aluminum oxide on the surface thereof. In theplasma processing apparatus 10 of the present invention, the energy ofincident plasma is low because of the low electron temperature of theexcited plasma, and the problem of metal contamination of the substrate12 by the sputtering of the process gas supply structure 31 is avoided.Further, it is possible to form the process gas supply structure 31 by aceramic such as alumina.

[0074] The lattice shaped process gas passages 31A and the process gasnozzle apertures 31B are formed so as to encompass an area slightlylarger than the substrate 12 represented in FIG. 4 by a broken line. Byproviding the process gas supply structure 31 between the shower plate14 and the substrate 12, the process gas is excited by the plasma anduniform processing becomes possible by using such plasma excited processgas.

[0075] In the case of forming the process gas supply structure 31 by aconductor such as a metal, the process gas supply structure 31 can forma shunting plane of the microwaves by setting the interval between thelattice shaped process gas passages 31A shorter than the microwavewavelength. In such a case, the microwave excitation.of plasma takesplace only in the space 11B, and there occurs excitation of the processgas in the space 11C including the surface of the substrate 12 by theplasma that has caused diffusion from the excitation space 11B. Further,such a construction can prevent the substrate from being exposeddirectly to the microwave at the time of ignition of the plasma, andthus, damaging of the substrate by the microwave is avoided.

[0076] In the microwave plasma processing apparatus 10 of the presentembodiment, the supply of the process gas is controlled uniformly by theprocess gas supply structure 31, and the problem of excessivedissociation of the process gas on the surface of the substrate 12 iseliminated. Thus, it becomes possible to conduct the desired substrateprocessing even in the case wherein there is formed a structure of largeaspect ratio on the surface of the substrate 12 up to the very bottom ofthe high aspect ratio structure. This means that the microwave plasmaprocessing apparatus 10 is effective for fabricating varioussemiconductor devices of different generations characterized bydifferent design rules.

[0077]FIG. 7 shows the schematic construction of the microwave sourceconnected to the coaxial waveguide 21 of FIG. 2A.

[0078] Referring to FIG. 7, the coaxial waveguide is connected to anedge of the waveguide extending from an oscillation part 25 includingtherein a magnetron 25A oscillating at the frequency of 2.45 GHz or 8.3GHz via an isolator 24, a power monitor 23 and a tuner 22 in this order.Thus, the microwave formed by the oscillator 25 is supplied to theradial line slot antenna 20, and the microwave reflected back from thehigh-density plasma formed in the plasma processing apparatus 10 isreturned again to the radial line slot antenna 20 after conducting animpedance adjustment by the tuner 22. Further, the isolator 24 is anelement having directivity and functions so as to protect the magnetron25A in the oscillation part 25 from the reflection wave.

[0079] In the microwave plasma processing apparatus 10 of the presentembodiment, the rapid change in impedance caused by the joint is reducedby forming the taper units 21At and 21Bt at the joint, or the powersupplying unit, between the coaxial waveguide 21 and the radial lineslot antenna 20. As a result, the reflection of microwaves caused by therapid change in impedance is suppressed, which makes the supplying ofmicrowaves from the coaxial waveguide 21 to the antenna 20 stable.

[0080] In addition, in the microwave plasma processing apparatus 10according to the present embodiment, as shown in a variation shown inFIG. 8, it is possible to replace the taper faces 21At and 21Bt withround faces 21Ar and 21Br, respectively. The change in impedance causedby the joint is further reduced by forming the round faces, whichresults in further efficient suppressing of the reflective wave.

[0081] In the microwave plasma processing apparatus 10 of the presentembodiment, the distance between the shower plate 14 exposed to the heatcaused by the plasma and the cooling unit is reduced substantially,compared with the conventional microwave plasma processing apparatus ofFIGS. 1A and 1B. As a result, it becomes possible to use a material suchas Al₂O₃ having a small dielectric loss and also a small thermalconductivity for the microwave transmission window in place of AlN,which is characterized by large dielectric loss. Thereby, the efficiencyof plasma processing and hence the processing rate are improved whilesimultaneously suppressing the temperature rise of the shower plate.

[0082] In the microwave plasma processing apparatus 10 of the presentembodiment, it is further noted that the gas including the reactionbyproduct formed in the space 11C as a result of the substrateprocessing forms a stable gas flow to the space 11A at the outersurrounding area because of the reduced distance between the showerplate 14 and the substrate 12 facing the shower plate 14, and thebyproduct is removed from the space 11C quickly. By maintaining thetemperature of the outer wall of the processing vessel 11 to be about150° C., it becomes possible to substantially eliminate the depositionof the reaction byproduct on the inner wall of the processing vessel 11,and the processing apparatus 10 quickly becomes ready for the nextprocess.

[0083] By the way, in the above description of the present embodiment,specific dimensions are mentioned, but the present invention is notlimited to such dimensions.

[0084] [Second Embodiment]

[0085]FIG. 9 shows the construction of the joint/supplying unit betweenthe coaxial waveguide 21 and the radial line antenna 20 according to asecond embodiment of the present invention. In FIG. 9, portionspreviously described are referred to by the same reference numerals, andtheir description will be omitted.

[0086] Referring to FIG. 9, the outer waveguide 21A constructing thecoaxial waveguide 21 and the body 17 of the radial line antenna 20 areconnected perpendicularly to each other forming the joint/supplying unitthat is perpendicularly bent. The inner conductor 21B is also connectedto the slot plate 16 perpendicularly.

[0087] Meanwhile, in the construction of FIG. 9, the retardation plate18 is made of Al₂O₃ having a high relative permittivity, and aring-shaped member 18A made of SiO₂, for example, is formed between theouter waveguide 21A and the inner conductor 21B so that an end of themember 18A contacts the retardation plate 18.

[0088] Because of this construction, the impedance changes stepwise, andthe reflective waves are reduced. The length of the member 18A can beoptimized based on the property of the antenna structure of the coaxialwaveguide 21 and the antenna 20.

[0089] In the embodiment of FIG. 9, the second edge face opposing thefirst edge face in contact with the retardation plate 18 is exposed toair. As is shown in FIG. 10, it is possible, however, to provide anotherring-shaped member 18B made of Teflon, for example, having smallerrelative permittivity on the second face of the ring-shaped member 18Aand to increase the number of steps in the impedance change at the jointunit.

[0090] Further, as is shown in FIG. 11, the ring-shaped member 18A maybe made of sintered mixture of SiO₂ and Si₃N₄ having differentpermittivity, and the mixture ratio of SiO₂ and Si₃N₄ in the ring-shapedmember 18A may be controlled so that the permittivity continuouslyincreases from the first edge face to the second edge face.

[0091]FIG. 12 shows the construction of the joint unit between thecoaxial waveguide 21 and the radial line antenna 20 according to anothervariation of the present embodiment. In FIG. 12, portions previouslydescribed are referred to by the same reference numeral, and theirdescription will be omitted.

[0092] Referring to FIG. 12, in this variation, the second edge face ofthe ring-shaped member 18A is considered to be a taper surface, and thethickness of the ring-shaped member 18A is linearly increased toward theretardation plate 18.

[0093] Using this construction, in the case where the ring-shaped member18A is made of the same material as the retardation plate 18 such asAl₂O₃, the impedance of the joint/supplying unit increases continuouslytoward the retardation plate 18, and reflection caused by the rapidchange in impedance is reduced, which results in an efficient and stablesupply of microwaves.

[0094] In addition, as is shown in FIG. 13, in a variation it is alsopossible to make the taper face of the ring-shaped member 18A a curvedsurface so that the thickness of the ring-shaped member 18A changesnon-linearly to the property of the joint/supplying unit. For example,it is possible to increase the thickness of the ring-shaped member 18Aexponentially.

[0095] Further, as is shown in FIG. 14, the ring-shaped member 18A maybe coupled with the construction of FIG. 3A having taper surfaces 21Atand 21Bt. In this case, the ring-shaped member 18A is not limited tothat of FIG. 9, but may be any construction of FIGS. 9 through 13.

[0096] [Third Embodiment]

[0097]FIG. 15 is a diagram showing the construction of a plasmaprocessing apparatus 10A according to a third embodiment of the presentinvention. In FIG. 15, the parts described earlier are referred to bythe same reference numerals, and their description is omitted.

[0098] Referring to FIG. 15, in the plasma processing apparatus 10A, theshower plate 14 is removed, and a plurality of plasma gas inlets 11P areformed, preferably in symmetry, in communication with the gas passagelip in the processing vessel 11. In the plasma processing apparatus 10Aaccording to the present embodiment, the construction is simplified, andthe fabrication cost can be reduced substantially.

[0099] In the plasma processing apparatus 10A thus constructed, thereflection of microwaves is reduced by forming the taper surfaces 21Atand 21Bt in the joint/supplying unit between the radial line slotantenna 20 and the coaxial waveguide 21, which results in an increase inthe power supplying efficiency, a reduction in abnormal discharge causedby the reflective waves, and an increased stability of the plasmaformation. In the present embodiment, the construction of the joint unitis not limited to that shown in FIG. 3A, and any construction of FIGS. 8through 14 can be used.

[0100] [Fourth Embodiment]

[0101]FIG. 16 is a diagram showing the construction of a microwaveplasma processing apparatus 10B according to a fourth embodiment of thepresent invention. In FIG. 16, parts that have been previously describedare referred to by the same numerals, and their description will beomitted.

[0102] Referring to FIG. 16, in the construction of the microwave plasmaprocessing apparatus 10B, the process gas supply structure 31 isremoved. Additionally, the entire face of the extending part 11 bholding the shower plate 14 is rounded out.

[0103] The plasma processing apparatus 10B thus constructed cannotperform film-forming or etching by supplying a process gas besides theplasma gas since the lower shower plate 31 is removed. The plasmaprocessing apparatus 10B, however, can form an oxidized layer, anitrified layer, or an oxidized-nitrified layer by supplying anoxidizing gas or a nitrifying gas from the shower plate 14 together withthe plasma gas.

[0104] In the plasma processing apparatus 10B thus constructed, thereflection of microwaves is reduced by forming the taper surfaces 21Atand 21Bt in the joint/supplying unit between the radial line slotantenna 20 and the coaxial waveguide 21, which results in an increase inthe power supplying efficiency, a reduction in abnormal discharge causedby the reflective waves, and an increased stability of the plasmaformation. In the present embodiment, the construction of the joint unitis not limited to that shown in FIG. 3A, and any construction of FIGS. 8through 14 can be used.

[0105] [Fifth Embodiment]

[0106] The joint/supplying structure according to the present inventionis not limited to the plasma processing apparatus 10 of FIG. 2A or itsvariation, and is applicable to the plasma processing apparatus 100using a conventional radial line slot antenna previously described byreferring to FIGS. 1A and 1B.

[0107]FIG. 17 shows the construction of a plasma processing apparatus100A according to a fifth embodiment of the present invention using thejoint/supplying structure of the present invention. In FIG. 17, theparts previously described are referred to by the same numerals, andtheir description will be omitted.

[0108] Referring to FIG. 17, the plasma processing apparatus 100A hassubstantially the same construction as the conventional plasmaprocessing apparatus 100, but is different in that the plasma processingapparatus 100A includes taper surfaces similar to the taper surfaces21At and 21Bt in the joint unit between the coaxial waveguide 110A andthe radial slot antenna body 110B or the slot plate 110D.

[0109] In the present embodiment, the reflection of microwaves isreduced by forming the taper surfaces in the joint/supplying unitbetween the coaxial waveguide 110A and the radial line slot antenna,which results in an increase in the power supplying efficiency, areduction in abnormal discharge caused by the reflective waves, and anincreased stability of the plasma formation. In the present embodiment,the construction of the joint unit is not limited to that shown in FIG.3A, and any construction of FIGS. 8 through 14 can be used.

[0110] [Sixth Embodiment]

[0111]FIG. 18 is a cross sectional view showing the entire constructionof a semiconductor fabrication apparatus 40 according to a sixthembodiment,of the present invention including the microwave plasmaprocessing apparatus 10 of FIGS. 2A and 2B.

[0112] Referring to FIG. 18, the semiconductor fabrication apparatus 40includes a vacuum transfer room 401 provided with a robot 405 having atransportation arm 415, and the microwave plasma processing apparatus 10is formed on the top face of the vacuum transfer room 401. In this case,the stage 13 can be moved up and down by a cylinder 406 covered by abellows 410. When the stage 13 descends to the end, the substrate 12 isset or taken out by the transportation arm 415. When the stage 13ascends to the end, the substrate 12 is shut off from the vacuumtransfer room 401 by a seal 410A and processed as desired.

[0113] A load lock room 402 having a stage 418 to hold a stack ofsubstrates, is provided at another position on the upper side of thevacuum transfer room 401. When the stage 418 ascends to the end, theload rock room 402 is shut off from the vacuum transfer room 401 by aseal 417. Meanwhile, when the stage 418 descends to the end, thesubstrate stack 404 descends to the vacuum transfer room 401, and thetransportation arm 415 picks up a substrate from the substrate stack 404or returns a processed substrate thereto.

[0114] In the case of semiconductor fabrication apparatus 40 thusconstructed, since a substrate is loaded and unloaded vertically, andnot through a side wall, an axially symmetry plasma is formed in theprocessing vessel 11, and a gas in the processing vessel is exhaustedthrough a plurality of exhaustion ports provided in an axial symmetry bya plurality of pumps. Accordingly, the semiconductor fabricationapparatus 40 can guarantee uniform plasma processing.

[0115]FIG. 19 shows the construction of an exhaustion system of theprocess unit A.

[0116] Referring to FIG. 19, in the process unit A, each exhaustion port11 a of the processing vessel 11 is connected to a duct D1, and a gas inthe processing vessel 11 is exhausted by screw molecular pumps P1 andP2, each having a construction as shown in FIGS. 14A and 14B, providedin the duct D1. The screw molecular pumps P1 and P2 are connected, attheir exhaustion side, to an exhaustion line D2 commonly provided to theother processing units B and C of the semiconductor fabricationapparatus 40. The exhaustion line D2 is connected to an exhaustion lineD3 commonly provided to the other semiconductor fabrication apparatusesvia an intermediate booster pump P3.

[0117]FIG. 20A shows the construction of the screw molecular pumps P1and P2.

[0118] Referring to FIG. 20A, the screw molecular pump has a cylindricalbody 51 and a pump inlet at an end part of the body 51 and a pump outleton the sidewall of the body 51 near the bottom part. In the body 51,there is provided a rotor 52 shown in FIG. 20B, and a gradational leadscrew 52A is formed on the rotor 52. It should be noted that thegradational lead screw 52A has a construction in which there is a largepitch formed at the pump inlet part and the pitch is decreased towardthe outlet. Associated with this, the lead angle of the screw isdecreased gradually from the inlet side toward the outlet side. Further,the volume of the pump chamber is decreased gradually from the inletside toward the outlet side.

[0119] Further, the screw molecular pump of FIG. 20A includes a motor 53provided in the rotor 52, an angle detector 54 detecting the angularposition of the rotor 52 and a magnet 55 cooperating with the angledetector 54, wherein the rotor 52 is urged toward the outlet side by anelectromagnet mechanism 56.

[0120] Such a screw molecular pump has a simple construction and isoperable over a wide pressure range from the atmospheric pressure toseveral millitorrs with small electric power consumption. Further, thescrew pump can obtain a pumping speed reaching 320 mL/min, which islarger than the pumping speed of conventional turbo molecular pumps.

[0121]FIG. 21 shows the construction of a gradational lead screw pump(GLSP) 60 used for the intermediate booster pump P3 for evacuating thescrew pumps P1 and P2 in the construction of FIG. 19.

[0122] Referring to FIG. 21, the gradational lead screw pump includes,in a pump body 61 having an inlet 61A at an end and outlets 63A and 63Bat another end, a pair of screw rotors 62A and 62B each changing a screwpitch thereof gradually from an inlet side to an outlet side as shown inFIG. 20B, in a meshing relationship of the screws, wherein the rotors62A and 62B are driven by a motor 64 via gears 63A and 63B.

[0123] The gradational lead screw pump 60 of such a construction isoperable over a wide pressure range from ordinary pressure to a lowpressure of as much as 10⁻⁴ Torr, and can achieve a flow rate reaching2,500 L/min.

[0124] In the construction of FIG. 19, in which the semiconductorfabrication apparatus is evacuated by the common back pump P4 via theintermediate booster pump P3, the back pump P4 is operated in the mostefficient pressure range, and the electric power consumption is reducedsubstantially.

[0125] In the construction of FIG. 19, the back pump P4 can operate atthe most efficient pressure range by exhausting the exhausted gas fromthe other semiconductor fabrication apparatus, which results in asubstantially reduced power consumption.

[0126]FIG. 22 shows the construction of the gas supplying systemcooperating with each of the processing units A-C in the semiconductorfabrication apparatus 40 of FIG. 18.

[0127] As explained before, the semiconductor fabrication apparatus 40avoids deposition of reaction byproduct formed associated with thesubstrate processing on the processing vessel 11 of the microwave plasmaprocessing apparatus 10 by maintaining the processing vessel 11 at atemperature of about 150° C. Thus, the processing unit of FIG. 19 has afeature that the memory or hysteresis of the preceding processing can beerased completely without conducting a specific cleaning process.

[0128] Thus, by using the processing unit of FIG. 19, it becomespossible to conduct different substrate processing one after another byswitching the plasma gas and/or process gas. For this, however, it isnecessary to provide a gas supply system that can switch the process gasquickly.

[0129] Referring to FIG. 22, one or two gases selected fro N₂, Kr, Ar,H₂, NF₃, C₄F₈, CHF₃, O₂, CO, HBr, SiCl₄ and the like, are supplied tothe plasma gas inlet port lip provided on the processing vessel 11 incommunication with the shower plate 14 through the first and/or secondflow rate control apparatuses FCS1 and FCS2, and one or more gasesselected from N₂, Kr, Ar, H₂, NF₃, C₄F₈, CHF₃, O₂, CO, HBr, SiCl₄ andthe like, are supplied to the process gas inlet port 11 r communicatingwith the process gas supply structure 30 via the third through seventhflow rate control apparatuses FCS3-FCS7.

[0130] By using a flow rate control apparatus as shown in FIG. 23,having a construction-in which a control valve 71, a manometer 72, astop valve 73 and an orifice 74 are formed consecutively on a straighttube 70 and by controlling the pressure P₂ at the downstream side of theorifice 74 to be equal to or smaller than one-half the pressure P₁ atthe upstream side of the stop valve 73 (P₁≧2P₂), it becomes possible tosupply the process gas instantaneously with a predetermined flow rate.This is because there is no dead space in the flow rate controlapparatus in which flow rate control is not possible.

[0131] Thus, by using the flow control apparatus of FIG. 23 in the gassupply system of FIG. 22, it becomes possible to switch the plasma gasor process gas instantaneously depending on the type of the substrateprocessing to be conducted in the processing unit.

[0132] In the semiconductor fabrication apparatus 40, it is noted thatnot only the plasma processing apparatus 10 but also the plasmaprocessing apparatuses according to the modifications thereof, or theplasma processing apparatuses 10A and 10B according to other embodimentscan also be used.

[0133] Further, the present invention is not limited to the specificembodiments noted above but various variations and modifications may bemade within the scope of the invention set forth in claims.

[0134] Industrial Applicability

[0135] According to the present invention, in the microwave plasmaprocessing apparatus, the rapid change in impedance caused by the jointbetween the coaxial waveguide providing microwaves and the microwaveantenna radiating the microwaves in the processing vessel of the plasmaprocessing apparatus is reduced. As a result, the reflection ofmicrowaves caused by the rapid change in impedance is suppressed, whichresults in forming stable microwave plasma in the processing vessel.

What is claimed is:
 1. A plasma processing apparatus, comprising: aprocessing vessel defined by an outer wall and having a stage forholding a substrate to be processed; an evacuation system coupled tosaid processing vessel; a microwave transparent window provided on saidprocessing vessel as a part of said outer wall, and opposite saidsubstrate held on said stage; a plasma gas supplying part for supplyingplasma gas to said processing vessel; a microwave antenna provided onsaid processing vessel in correspondence to said microwave; and amicrowave power source electrically coupled to said microwave antenna,wherein said microwave antenna comprising a coaxial waveguide connectedto said microwave power source, said coaxial waveguide having an innerconductor core and an outer conductor tube surrounding said innerconductor core, and an antenna body provided to a point of said coaxialwaveguide; said antenna body further comprising a first conductorsurface forming a microwave radiation surface coupled with saidmicrowave transparent window, and a second conductor surface oppositesaid first conductor surface via a dielectric plate, said secondconductor surface being connected to said first conductor surface at aperipheral part of said dielectric plate; said inner conductor core isconnected to said first conductor surface by a first joint unit; saidouter conductor tube is connected to said second conductor surface by asecond joint unit; said first joint unit forms a first taper unit inwhich an outer diameter of said inner conductor core increases towardsaid first conductor surface; and said second joint unit forms a secondtaper unit in which an inner diameter of said outer conductor tubeincreases toward said first conductor surface.
 2. The microwave plasmaprocessing apparatus as claimed in claim 1, wherein the distance betweenan outer surface of said inner conductor core and an inner surface ofsaid outer conductor tube increases toward said first conductor surface.3. The microwave plasma processing apparatus as claimed in claim 1,wherein said first taper unit is defined by a first curved surface; andsaid second taper unit is defined by a second curved surface.
 4. Themicrowave plasma processing apparatus as claimed in claim 1, furthercomprising a dielectric member provided in a space between said innerconductor core and said outer conductor tube, defined by a first edgeface and a second edge face opposing said first edge face, said firstedge face being adjacent to said dielectric plate, a permittivity ofsaid dielectric member being lower than a permittivity of saiddielectric plate and higher than a permittivity of air.
 5. The microwaveplasma processing apparatus as claimed in claim 4, wherein compositionof said dielectric member is changed from said first edge face to saidsecond edge face.
 6. The microwave plasma processing apparatus asclaimed in claim 4, wherein said dielectric plate is made of eitheralumina, silicon oxide, silicon oxynitrided, or silicon nitrided; andsaid dielectric member is made of silicon oxide.
 7. The microwave plasmaprocessing apparatus as claimed in claim 4, further comprising anotherdielectric member in a space between said inner conductor core and saidouter conductor tube, adjacent to said second edge face of saiddielectric member, a permittivity of said other dielectric member beinglower than a permittivity of said dielectric member and higher than apermittivity of air.
 8. The microwave plasma processing apparatus asclaimed in claim 7, wherein said dielectric member is made of siliconoxide, and said other dielectric member is made of Teflon.
 9. Themicrowave plasma processing apparatus as claimed in claim 4, whereinsaid second edge face of said dielectric member forms a taper surface;and an outer diameter of said dielectric member decreases as a distancefrom said first edge face increases.
 10. The microwave plasma processingapparatus as claimed in claim 9, wherein an outer diameter of saiddielectric member linearly decreases as a distance from said first edgeface increases.
 11. The microwave plasma processing apparatus as claimedin claim 9, wherein an outer diameter of said dielectric memberexponentially decreases as a distance from said first edge faceincreases.
 12. The microwave plasma processing apparatus as claimed inclaim 1, wherein said plasma gas supplying part further comprises aplasma gas passage connectable to a plasma gas source, said plasma gaspassage being made of a microwave-transparent material, and a showerplate having a plurality of openings in communication with said plasmagas passage, provided in an interior of said microwave transparentwindow in intimate contact.
 13. The microwave plasma processingapparatus as claimed in claim 12, wherein said shower plate is made ofalumina.
 14. The microwave plasma processing apparatus as claimed inclaim 1, wherein said plasma gas supplying part is provided in an outerwall of said processing vessel.
 15. The microwave plasma processingapparatus as claimed in claim 14, wherein said plasma gas supplying partis tubes provided in said outer wall of said processing vessel.
 16. Theplasma processing apparatus as claimed in claim 1, wherein saidmicrowave antenna is provided so that said first conductor surfacetouches said microwave transparent window.
 17. The plasma processingapparatus as claimed in claim 1, wherein said microwave antenna isprovided so that said first conductor surface is spaced from saidmicrowave transparent window.
 18. The plasma processing apparatus asclaimed in claim 1, wherein a processing gas source is provided betweensaid substrate and said plasma gas supplying part, in said processingvessel, said processing gas supplying part opposing to said substrate; afirst opening through which plasma formed in said processing vesselpasses and a second opening through which processing gas is provided;and said second opening is in communication with a processing gaspassage connected to a processing gas source, formed in said processinggas supplying source.
 19. A plasma processing apparatus, comprising: aprocessing vessel defined by an outer wall and having a stage forholding a substrate to be processed; an evacuation system coupled tosaid processing vessel; a microwave transparent window provided on saidprocessing vessel as a part of said outer wall, opposite said substrateheld on said stage; a plasma gas supplying part for supplying plasma gasto said processing vessel; a microwave antenna provided on saidprocessing vessel in correspondence to said microwave; and a microwavepower source electrically coupled to said microwave antenna, whereinsaid microwave antenna comprising a coaxial waveguide connected to saidmicrowave power source, said coaxial waveguide having an inner conductorcore and an outer conductor tube surrounding said inner conductor core,and an antenna body provided to a point of said coaxial waveguide; saidantenna body further comprising a first conductor surface forming amicrowave radiation surface coupled with said microwave transparentwindow, and a second conductor surface opposite said first conductorsurface via a dielectric plate, said second conductor surface beingconnected to said first conductor surface at a peripheral part of saiddielectric plate; said inner conductor core is connected to said firstconductor surface by a first joint unit; said outer conductor tube isconnected to said second conductor surface by a second joint unit; adielectric member is provided in a space between said inner conductorcore and said outer conductor tube, defined by a first edge face and asecond edge face opposing said first edge face, said first edge facebeing adjacent to said dielectric plate, a permittivity of saiddielectric member being lower than a permittivity of said dielectricplate and higher than a permittivity of air.
 20. The plasma processingapparatus as claimed in claim 19, wherein said inner conductor core isconnected substantially perpendicularly to said first conductor surfacein said first joint unit.
 21. The plasma processing apparatus as claimedin claim 19, wherein, in said second joint unit, said outer conductorcore is connected substantially perpendicularly to said second conductorsurface.
 22. The plasma processing apparatus as claimed in claim 19,wherein composition of said dielectric member changes from said firstedge face to said second edge face.
 23. The plasma processing apparatusas claimed in claim 19, wherein said dielectric plate is made of eitheralumina, silicon oxide, silicon oxynitridated, or silicon nitridated;and said dielectric member is made of silicon oxide.
 24. The plasmaprocessing apparatus as claimed in claim 21, wherein, in a space betweensaid inner conductor core and said outer waveguide, another dielectricmember having a permittivity lower than a permittivity of saiddielectric member and higher than a permittivity of air is providedadjacent to said second edge face of said dielectric member.
 25. Theplasma processing apparatus as claimed in claim 24, wherein saiddielectric member is made of silicon oxide, and said other dielectricmember is made of Teflon.
 26. The plasma processing apparatus as claimedin claim 21, wherein said second edge face of said dielectric memberforms a taper surface, and an outer diameter of said dielectric memberdecreases as a distance from said first edge face increases.
 27. Theplasma processing apparatus as claimed in claim 26, wherein an outerdiameter of said dielectric member decreases linearly as a distance fromsaid first edge face increases.
 28. The plasma processing apparatus asclaimed in claim 26, wherein an outer diameter of said dielectric memberdecreases exponentially as a distance from said first edge faceincreases.
 29. The plasma processing apparatus as claimed in claim 19,wherein said plasma gas supplying part is provided with a plasma gaspassage connectible to a plasma gas source, made of a microwavetransparent material, and a shower plate having a plurality of openingsin communication with said plasma gas passage.
 30. The plasma processingapparatus as claimed in claim 29, wherein said microwave transparentwindow and said shower plate are made of alumina.
 31. The plasmaprocessing apparatus as claimed in claim 19, wherein said plasma gassupplying part is provided in an outer wall of said processing vessel.32. The plasma processing apparatus as claimed in claim 31, wherein saidplasma gas supplying part is tubes provided in said processing vessel.33. The plasma processing apparatus as claimed in claim 19, wherein saidmicrowave antenna is provided so that said first conductor surfacetouches said microwave transparent window.
 34. The plasma processingapparatus as claimed in claim 19, wherein said microwave antenna isprovided so that said first conductor surface separates from saidmicrowave transparent window.
 35. The plasma processing apparatus asclaimed in claim 19, wherein a process gas supplying part is providedbetween said substrate and said plasma gas supplying part in saidprocessing vessel, said process gas supplying part opposing to saidsubstrate; a first opening through which plasma gas formed in saidprocessing vessel passes and a second opening through which process gasis supplied are formed in said process gas supplying part; and saidsecond opening is connected to a process gas passage formed in saidprocess gas supplying part and connected to a process gas source.